Technical Field
The present invention relates to a fixing device and an image forming apparatus including the same.
Background Art
In an image forming apparatus employing electrophotography, an electrostatic latent image is first formed on a surface of a photoconductor, the electrostatic latent image is developed by toner as a developer and is rendered visible as a toner image, the developed toner image is transferred to a recording sheet by a transfer device, and subsequently, the image is fixed onto the recording sheet as a final image by a fixing device.
A typical fixing device includes a pressure belt, a heating roller that contacts an outer circumferential surface of the pressure belt, a pressure pad that presses the pressure belt against the outer circumferential surface of the heating roller from an internal circumferential surface of the pressure belt, and a heater to heat the heating roller.
Such a fixing device is configured such that the heating roller is driven to rotate, the pressure belt is driven by the rotation of the heating roller, and when a recording sheet on which a toner image is transferred is passed between the pressure belt and the heating roller with the heating roller heated by the heater, the toner image is fused and fixed onto the recording sheet.
However, the recording sheet heated at the nip portion curls sharply toward a side on which no image is formed, due to a difference in temperature between the side of the recording sheet on which the image is formed and on which the toner image is fused and fixed by the heating roller, on the one hand, and the side on which no image is formed and supported by the pressure belt on the other. If the curl amount of the recording sheet is prominent, a paper jam may occur in a sheet feeding path or a sheet ejection outlet of the image forming apparatus.